Heat transfer device having 3-dimensional projections and an associated method of fabrication

ABSTRACT

A heat transfer device filled with a working fluid, includes a casing and a wick disposed within the casing. The wick includes a first sintered layer, a second sintered layer, and a third sintered layer. The first sintered layer is disposed proximate to an inner surface of the casing and the second sintered layer is disposed on the first sintered layer. The second sintered layer includes a first set of 3-dimensional sintered projections and a second set of 3-dimensional sintered projections disposed along a portion of the wick. Further, the third sintered layer is disposed on at least a portion of the second sintered layer. The heat transfer device includes at least one first sintered particle of the first sintered layer, which is smaller in size than at least one second pore of the second sintered layer.

BACKGROUND

The present disclosure relates generally to a heat transfer device and more particularly, to a vapor chamber or a heat pipe having 3-dimensional sintered projections, a spatially controlled porosity or pore size, and an associated method of fabrication.

A heat transfer device is used to transfer heat from a source to a sink. Such heat transfer devices may include a hot region and a cold region to enable transfer of the heat from the hot region to the cold region. Generally, the heat transfer device combines the principle of a thermal conductivity and a phase transition of a working fluid to transfer the heat. In one example, the heat transfer device is a sealed tube or a sealed chamber, fabricated using a material having a high thermal conductivity. The heat transfer device includes the working fluid within the sealed chamber to transfer the heat effectively. Typically, such heat transfer device may further include a wick to enable heat transfer by condensation and evaporation of the working fluid i.e. by changing phase of the working fluid within the sealed chamber.

The conventional wick includes a plurality of mono-dispersed sintered particles distributed along a longitudinal direction of the heat transfer device. Typically, wicks are also designed to provide a high fluid transport and phase change capability of the working fluid. Such functions are achieved by designing the wick having very large pores combined with a large surface area, for facilitating phase change of the working fluid. However, such conventional wicks are less effective in performing phase change of the working fluid, because the design and fabrication processes involve use of mono-dispersed particles. Further, such a wick structure provides higher solid conduction thermal resistance due to low contact area with the chamber walls.

Such limitations can be addressed by designing the wick, having pore size variation through the use of varying particle sizes. However, the wicks that are designed with varying particle sizes are fabricated using an organic carrier which is burned completely to generate the sintered particles having varied pore size and/or varied porosity. Such fabrication processes may result in contamination of the heat transfer device, limit the wick fabrication temperature to a high value to burn-away the organics, and may also lead to generation of a non-condensable fluid during prolonged operation of the heat transfer device.

Further, the wick having dissimilar material is used to reduce the thermal resistance and increase evaporation limit of the heat transfer device. However, such wicks may require complex processes to fabricate, may undergo galvanic corrosion, and may not be very effective in reducing the thermal resistance and increasing evaporation limit in the heat transfer device.

Thus, there is a need for an improved heat transfer device and a method for fabricating the heat transfer device.

BRIEF DESCRIPTION

In accordance with one exemplary embodiment, a heat transfer device is disclosed. The heat transfer device includes a casing and a wick disposed within the casing. The wick includes a first sintered layer disposed proximate to an inner surface of the casing and a second sintered layer disposed on the first sintered layer. The first sintered layer includes a plurality of first sintered particles, having a first porosity and a plurality of first pores. The second sintered layer includes a plurality of second sintered particles, having a second porosity and a plurality of second pores. The second sintered layer further includes at least one set among a first set of 3-dimensional sintered projections and a second set of 3-dimensional sintered projections disposed along a portion of the wick. At least one first sintered particle is smaller than at least one second pore and the first porosity is smaller than the second porosity The wick further includes a third sintered layer disposed on at least a portion of the second sintered layer. The third layer includes a plurality of third sintered particles, having a third porosity and a plurality of third pores.

In accordance with one exemplary embodiment, a method for manufacturing a heat transfer device is disclosed. The method includes forming a first wick portion within a first half casing portion and a second wick portion within a second half casing portion. The first wick portion includes a first sintered layer portion, a second sintered layer portion, and a third sintered layer portion. The second wick portion includes another first sintered layer portion, another second sintered layer portion, and another third sintered layer portion. Each first sintered layer portion includes a plurality of first sintered particles, having a first porosity and a plurality of first pores. Each second sintered layer includes a plurality of second sintered particles, having a plurality of second pores and a second porosity. The second sintered layer further includes at least one set among a first set of 3-dimensional sintered projections and a second set of 3-dimensional sintered projections disposed along a portion of the wick. Each third sintered layer portion includes a plurality of third sintered particles, having a plurality of third pores and a third porosity. The method further includes coupling the first half casing portion to the second half casing portion such that the first wick portion is coupled to the second wick portion to form a heat transfer device. The fabricated heat transfer device includes at least one first sintered particle smaller than at least one second pore. Further, the second porosity is greater than the first porosity and the third porosity is smaller than the second porosity.

DRAWINGS

These and other features and aspects of embodiments of the present disclosure will become better understood when the following detailed description is read with reference to the accompanying drawings in which like characters represent like parts throughout the drawings, wherein:

FIG. 1 is a schematic sectional view of a heat transfer device, for example a heat pipe, in accordance with an exemplary embodiment;

FIG. 2 is a schematic sectional view of a portion of a wick disposed within a heat pipe in accordance with the exemplary embodiment of FIG. 1;

FIG. 3 is a schematic view of a portion of a wick of FIGS. 1 and 2, having a plurality of first sintered particles, a plurality of second sintered particles, and a plurality of third sintered particles in accordance with an exemplary embodiment;

FIG. 4 a is a top view of a schematic heat transfer device, for example a vapor chamber in accordance with an exemplary embodiment;

FIG. 4 b is a schematic side view of a vapor chamber of FIG. 4 a, in accordance with an exemplary embodiment;

FIG. 5 a is a schematic flow diagram illustrating a method for manufacturing a first wick portion within a first half casing portion in accordance with an exemplary embodiment;

FIG. 5 b is a schematic flow diagram illustrating the method for manufacturing the first wick portion within the first half casing portion in accordance with an exemplary embodiment of FIG. 5 a;

FIG. 6 a is a schematic flow diagram illustrating a method for manufacturing a second wick portion within a second half casing portion in accordance with an exemplary embodiment;

FIG. 6 b is a schematic flow diagram illustrating the method for manufacturing the second wick portion within the second half casing portion in accordance with an exemplary embodiment of FIG. 6 a;

FIG. 7 is a schematic flow diagram illustrating a method for manufacturing a heat transfer device by coupling a first half casing portion to a second half casing portion in accordance with the exemplary embodiments of FIGS. 5 a, 5 b, 6 a, and 6 c;

FIG. 8 a is a schematic flow diagram illustrating a method for manufacturing a heat transfer device in accordance with another exemplary embodiment;

FIG. 8 b is a schematic flow diagram illustrating the method for manufacturing the heat transfer device in accordance with the exemplary embodiment of FIG. 8 a;

FIG. 8 c is a schematic flow diagram illustrating the method for manufacturing the heat transfer device in accordance with the exemplary embodiments of FIGS. 8 a and 8 b;

FIG. 8 d is a schematic flow diagram illustrating the method for manufacturing the heat transfer device in accordance with the exemplary embodiments of FIGS. 8 a, 8 b, and 8 c;

FIG. 9 a is a schematic flow diagram illustrating a method for manufacturing a heat transfer device in accordance with yet another exemplary embodiment;

FIG. 9 b is a schematic flow diagram illustrating the method for manufacturing the heat transfer device in accordance with the exemplary embodiment of FIG. 9 a; and

FIG. 9 c is a schematic flow diagram illustrating the method for manufacturing the heat transfer device in accordance with the exemplary embodiments of FIGS. 9 a and 9 b.

DETAILED DESCRIPTION

While only certain features of embodiments have been illustrated and described herein, many modifications and changes will occur to those skilled in the art. It is, therefore, to be understood that the appended claims are intended to cover all such modifications and changes as falling within the spirit of the invention.

Embodiments discussed herein disclose heat transfer devices and associated methods of manufacturing the heat transfer devices. More particularly, certain embodiments disclose a heat pipe. The heat pipe includes a casing and a wick disposed within the casing. The wick includes a first sintered layer, a second sintered layer, and a third sintered layer. The first sintered layer includes a plurality of first sintered particles having a first porosity and a plurality of first pores. The first sintered layer is disposed proximate to the inner surface of the casing. The second sintered layer includes a plurality of second sintered particles having a second porosity and a plurality of second pores. The second sintered layer is disposed on the first sintered layer. The second sintered layer further includes a set of 3-dimensional projections disposed on a portion of the second sintered layer. The third sintered layer includes a plurality of third sintered particles having a third porosity and a plurality of third pores. At least one first sintered particle is smaller than at least one second pore, the first porosity is smaller than the second porosity, and the third porosity is smaller is than second porosity.

Certain embodiments disclose a method of manufacturing a heat transfer device. More specifically, certain embodiments disclose a method of manufacturing a vapor chamber. The method includes forming a first wick portion having a first sintered layer portion, a second sintered layer portion, and third sintered layer portion within a first half casing portion. Further, the method includes forming a second wick portion having another first sintered layer portion, another second sintered layer portion, and another third sintered layer portion within a second half casing portion. The method further includes coupling the first half casing portion to the second half casing portion such that the first wick portion is coupled to the second wick portion to form a heat transfer device. Each first sintered layer portion includes a plurality of first sintered particles, having a first porosity and a plurality of first pores. Each second sintered layer portion includes a plurality of second sintered particles, having a plurality of second pores and a second porosity. At least one second sintered layer portion includes a set of 3-dimensional sintered projections. Each third sintered layer portion includes a plurality of third sintered particles, having a plurality of third pores and a third porosity. Further, at least one first sintered particle is smaller than at least one second pore.

FIG. 1 is a schematic sectional view of a heat transfer device 100. In the illustrated embodiment, the heat transfer device 100 is a heat pipe. It should be noted herein that the terms “heat transfer device” and “heat pipe” are used interchangeably. In some other embodiments, the heat transfer device is a vapor chamber.

The heat pipe 100 includes a casing 102 and a wick 104. Further, the heat pipe 100 includes a sealed chamber 106 enclosed by the wick 104 and a working fluid 108 filled within the sealed chamber 106. The working fluid 108 transfers heat from one region 116 to another region 118 of the heat pipe 100. Further, the heat pipe 100 includes an evaporator section 110 disposed proximate to the region 116, a condenser section 112 disposed proximate to the other region 118, and a transport section 114 disposed between the evaporator section 110 and the condenser section 112. The evaporator section 110 is configured to absorb heat from a source (not shown in FIG. 1) by evaporating the working fluid 108. The condenser section 112 is configured to release heat to a sink (not shown in FIG. 1) by condensing the working fluid 108. The transport section 114 is configured to conduct the heat from one region 116 to the other region 118 via the working fluid 108. The heat pipe 100 is fabricated using a material having high thermal conductivity. The material may include copper or aluminum nitrate, for example. The heat pipe 100 has a rectangular shape and has a length “L₁” in a range of five millimeters to ten meters, for example.

The casing 102 includes a first half casing portion 102 a and a second half casing portion 102 b. Each half casing portion 102 a, 102 b includes an inner surface 120 and an outer surface 122. Each half casing portion 102 a, 102 b has a U-shape. The first half and second half casing portions 102 a, 102 b are coupled to each other by welding, brazing, soldering, or the like. The wick 104 is disposed proximate to the inner surface 120 of the casing 102. The wick 104 includes a first sintered layer 126, a second sintered layer 128, and a third sintered layer 130. Specifically, the first sintered layer 126 is disposed proximate to the inner surface 120 of the casing 102. The second sintered layer 128 is disposed on the first sintered layer 126. The second sintered layer 128 includes at least one of a first set of 3-dimensional sintered projections 132 and a second set of 3-dimensional sintered projections 134. The first and second set of 3-dimensional sintered projections 132, 134 are disposed along a portion of the wick 104 corresponding to the evaporator section 110, for example. The third sintered layer 130 is disposed on at least a portion of the second sintered layer 128 corresponding to the evaporator section 110, for example.

The wick 104 includes a first wick portion 104 a and a second wick portion 104 b. Specifically, the first wick portion 104 a includes the first sintered layer portion 126 a, the second sintered layer portion 128 a, and the third sintered layer portion 130 a. The second wick portion 104 b includes another first layer portion 126 b, another second sintered layer portion 128 b, and another third sintered layer portion 130 b. The first, second, and third sintered layers 126, 128, 130 have a uniform thickness “T₁”, “T₂”, and “T₃” respectively along the length “L₁” of the heat pipe 100. In another embodiment, the first, second, and third sintered layers 126, 128, 130 may have a non-uniform thickness along the length “L₁” of the heat pipe 100. The thickness may vary along the evaporator section 110, the condenser section 112 and the transport section 114 of the heat pipe 100. The casing 102 is made of a first material and the first sintered layer 126, the second sintered layer 128, and the third sintered layer are made of a second material. The casing 102, the first sintered layer 126, and the second sintered layer 128 are made of the same material. The first, second, and third sintered layers 126, 128, 140 are made of a material having high thermal conductivity, such as copper, aluminum nitrate, or the like.

FIG. 2 is a schematic sectional view of a portion of the wick 104 corresponding to the evaporator section 110 of the heat pipe 100 in accordance with the embodiment of FIG. 1.

The wick 104 includes the first set of 3-dimensional sintered projections 132 extending from a first side 136 of the wick 104 towards a second side 138 of the wick 104. Further, the wick 104 includes the second set of 3-dimensional sintered projections 134 extending from the first side 136 to the second side 138 of the wick 104. The first and second set of 3-dimensional sintered projections 132, 134 is spaced apart from each other by a distance “D₁” along a longitudinal direction. The first set of 3-dimensional projections 132 and the second set of 3-dimensional projections 134 are disposed alternately. The position of the first set of 3-dimensional projections 132 and the second set of 3-dimensional projections 134 may vary depending on the application and design criteria. The third sintered layer 130 is disposed on the first and second set of 3-dimensional sintered projections 132, 134, at the evaporator section 110. In other embodiments, the wick 104 may not include the third sintered layer 130.

The first set of 3-dimensional sintered projections 132 enhances a surface area of the wick 104. The first set of 3-dimensional sintered projections is configured to convert the working fluid 108 from one phase to another phase, for example, from a liquid phase to gaseous phase. The first set of 3-dimensional sintered projections 132 increases a surface area at the evaporator section 110 to absorb the heat from the sink (not shown). The second set of 3-dimensional sintered projections 134 is configured to transport the working fluid 108 from the second side 138 to the first side 136 of the wick 104. Further, the second set of 3-dimensional projections 134 provides structural support to the heat transfer device 100 so as to prevent mechanical deformation, vibration, shock loading and temperature excursions during assembling or operation of the heat transfer device 100. In another embodiment, the second set of 3-dimensional projections 134 includes solid projections integrated to the casing 102. The second set of 3-dimensional sintered projections 134 enhances transportation of the working fluid 108 at the evaporator section 110. In other embodiments, the working fluid 108 may be transported from the first side 136 to the second side 138 of the wick 104 via the second set of 3-dimensional sintered projections 134. The first set of 3-dimensional sintered projections 132, the second set of 3-dimensional sintered projections 134, and the third sintered layer 130 may be disposed at the condenser section 112 of the heat pipe 100.

FIG. 3 is a schematic view of a portion of the wick 104 in accordance with the exemplary embodiments of FIGS. 1 and 2. As discussed previously, the wick 104 includes the first sintered layer 126, the second sintered layer 128, and the third sintered layer 130. The first sintered layer 126 includes a plurality of first sintered particles 148, the second sintered layer 128 includes a plurality of second sintered particles 150, and the third sintered layer 130 includes a plurality of third sintered particles 152. Further, the first sintered layer 126 has a plurality of first pores 154 and a first porosity 156, the second sintered layer 128 has a plurality of second pores 158 and a second porosity 160, and the third sintered layer 130 has a plurality of third pores 162 and a third porosity 164.

Each first sintered particle 148 has a size “S₁”, each second sintered particle 150 has a size “S₂”, and each third sintered particle 152 has a size “S₃”. Further, each first pore 154 has a size “S₄”, each second pore 158 has a size “S₅” and each third pore 162 has a size “S₆”. Each first sintered particle 148 has the size “S₁” in a range of hundred nanometers to fifty micrometers, each second sintered particle 150 has the size “S₂” in a range of ten micrometers to hundred micrometers, and each third sintered particle 152 has the size “S₃” in a range of hundred nanometers to ten micrometers. The size “S₂” of each second sintered particle 150 is greater than the size “S₁” of each first sintered particle 148 and the size “S₃” of each third sintered particle 152 is smaller or equal to the size “S₂” of each second sintered particle 150. Each first sintered particle 148, each second sintered particle 150, and each third sintered particle 152 may have a spherical or oval or circular shape.

The size “S₁” of each first sintered particle 148 is smaller than the size “S₅” of each second pore 158. The size “S₁” of the first sintered particle 148 is at least twenty to eighty percent smaller than the size “S₅” of the plurality of second pores 158. The first sintered particle 148 having a relatively smaller size than the second pore 158 enhances heat transfer capability and reduces thermal resistance along the longitudinal direction of the heat pipe 100.

Further, each first pore 154 has the size “S₄” in a range of ten nanometers to ten micrometers, each second pore 158 has the size “S₅” in a range of one micrometer to fifty micrometers, and each third pore 162 has a size “S₆” in the range of one nanometer to ten micrometers.

The first porosity 156 of the first sintered layer 126, the second porosity 160 of the second sintered layer 128, and third porosity 164 of the third sintered layer 130 are in a range of five percent to eighty percent. The first porosity 156 is smaller than the second porosity 160 and the third porosity 164 is smaller than the second porosity 160. The second layer 128 having a relatively greater second porosity 152 facilitates to exert higher capillary pressure on the working fluid along the longitudinal direction of the heat pipe 100.

FIG. 4 a is a top view of a heat transfer device 101, for example a vapor chamber, in accordance with another exemplary embodiment. It should be noted herein that the terms “heat transfer device” and the “vapor chamber” are used interchangeably.

The vapor chamber 101 includes a casing 103 and a wick (not shown in FIG. 4 a) disposed within the casing 103. The vapor chamber 101 includes an evaporator section 165, a condenser section 167, and a transport section 169. The evaporator section 165 is configured to absorb heat from a source (not shown in FIG. 4 a) by evaporating the working fluid (not shown in FIG. 4 a). The condenser section 167 is configured to release heat to a sink (not shown in FIG. 4 a) by condensing the working fluid. The transport section 169 is configured to conduct the heat from the evaporator section 165 to the condenser 167 and vice versa, via the working fluid. The vapor chamber 101 includes two condenser sections 167 disposed at either ends 171, 173 of the vapor chamber 101.

FIG. 4 b is a schematic side view along a section 4 b-4 b of the vapor chamber 101 in accordance with the exemplary embodiment of FIG. 4 a. The vapor chamber 101 includes the wick 105 disposed proximate to an inner surface 121 of the casing 103. The wick 105 includes a first sintered layer 127, a second sintered layer 129, and a third sintered layer 131. The second sintered layer 129 includes a first set of 3-dimensional sintered projections 133 and a second set of 3-dimensional sintered projections 135 disposed on a portion of the wick 105. The portion of the wick corresponds to the evaporator section 165 and the condenser section 167. The first set of 3-dimensional sintered projections 133 are disposed at the evaporator section 165 and extend from a first side 137 towards a second side 139 of the wick 105. The second set of 3-dimensional projections 135 are disposed at the evaporator section 165 and the condenser section 167 and extend from the first side 137 to the second side 139 of the wick 105. The third sintered layer 131 is disposed on the second sintered layer 129 and the first and second set of 3-dimensional sintered projections 133, 135.

A coating 175 is disposed between the inner surface 121 of the casing 103 and the first sintered layer 127. The coating 175 may include one or more layers depending on the application and design criteria. The casing 103 may be made of a material having higher thermal conductivity, for example, aluminum nitrate. The coating 175 and the wick 105 may be also made of a material having high thermal conductivity, for example copper. The casing 103 may be made of a first material and the coating 175, the first sintered layer 127, the second sintered layer 129, and the third sintered layer 131 made of a second material different from the first material.

FIG. 5 a is a schematic flow diagram illustrating a plurality of steps involved in a method 176 of manufacturing the first sintered layer portion 126 a, the second sintered layer portion 128 a, the set of 3-dimensional projections 132, and the third sintered layer portion 130 a within the first half casing portion 102 a in accordance with the embodiment of FIG. 1.

The method 176 includes a step 178 of disposing the first half casing portion 102 a. Further, the method 176 includes a step 180 of applying a coating portion 175 a on the inner surface 120 of the first half casing portion 102 a. A plurality of first particles 182 and a plurality of second particles 184 are filled in the first half casing portion 102 a. The first half casing portion 102 a is made of a first material and the coating portion 175 a, the plurality of first particles 182, and the plurality of second particles 184 includes a second material different from the first material.

In another embodiment, a coating portion 175 a may not be applied to the inner surface 120 of the first half casing portion 102 a and the plurality of particles 182, 184 are filled directly within the first half casing portion 102 a such that the plurality of particles 182, 184 are in contact with the inner surface 120 of the first half casing portion 102 a. The first half casing portion 102 a, the plurality of first particles 182, and the plurality of second particles 184 include same material.

A step 186 includes leveling the plurality of first particles 182 and the plurality of second particles 184 within the first half casing portion 102 a. The plurality of first and second particles 182, 184 is leveled using a squeegee device 188. A uniform contact surface 190 of the squeegee device 188 is used to level the plurality of first particles 182 and the plurality of second particles 184 to generate a uniform thickness. The squeegee device 188 may be made of a material including nickel-cobalt ferrous alloy or ceramics such as aluminum nitrate, alumina, silicon carbide, silicon nitride, or the like.

The method 176 further includes a step 192 of vibrating the first half casing portion 102 a to segregate the plurality of first particles 182 from the plurality of second particles 184 such that a first layer portion 194 a and a second layer portion 196 a are formed within the first half casing portion 102 a. The first half casing portion 102 a is vibrated via a vibrator device 198. The vibrator device 198 is clamped to the first half casing portion 102 a and powered via mechanical elements to vibrate the first half casing portion 102 a. The first layer portion 194 a having the plurality of first particles 182 is disposed proximate to the inner surface 120 of the first half casing portion 102 a and the second layer portion 196 a having the plurality of second particles 184 is disposed on the first layer portion 194 a. The first layer portion 194 a has a uniform thickness “T₀₁” and the second layer portion 196 a has a uniform thickness “T₀₂”.

The method 176 further includes a step 200 of disposing a set of hollow sintering spacers 202 on the second layer portion 196 a. Each spacer 202 has a uniform contact surface 204 contacting the second layer portion 196 a. At step 206, an additional amount of the plurality of second particles 184 is filled between the hollow sintering spacers 202 to form a set of 3-dimensional projections 208, also referred to as a first set of 3-dimensional projections. Further, a step 210 includes disposing a sintering weight 212 on the set of hollow sintering spacers 202 to level the plurality of second particles 184 filled between the hollow sintering spacers 202. At step 214, an additional amount of the plurality of second particles 184 is filled in a gap between the hollow sintering spacers 202 and a side 216 of the inner surface 120.

FIG. 5 b is a schematic flow diagram illustrating a plurality of steps involved in the method 176 of manufacturing the first sintered layer portion 126 a, the second sintered layer portion 128 a, the set of 3-dimensional projections 132, and the third sintered layer portion 130 a within the first half casing portion 102 a in accordance with the embodiment of FIG. 5 a. The method 176 further includes a step 222 of sintering the first layer portion 194 a and the second layer portion 196 a. The step 222 includes disposing the first half casing portion 102 a with the set of hollow sintering spacers 202 and sintering weight 212 in a sintering device 224 to sinter the first layer portion 194 a and the second layer portion 196 a so as to generate the first sintered layer portion 126 a and the second sintered layer portion 128 a having a set of 3-dimensional sintered projections 132, also referred to as the first set of 3-dimensional sintered projections, as shown in step 226. The first sintered layer portion 126 a and the second sintered layer portion 128 a have a uniform thickness. The first sintered layer portion 126 a has a thickness “T₁” and the second sintered layer portion 128 a has a thickness “T₂”.

The first sintered layer portion 126 a includes the plurality of first sintered particles 148 having the first porosity 156 and the plurality of first pores 154 (as shown in FIG. 3). The second sintered layer portion 128 a includes the plurality of second sintered particles 150 having the plurality of second pores 158 and the second porosity 160 (as shown in FIG. 3). The sintering step 222 is performed in a controlled environment i.e. at a temperature and pressure so as to generate at least one first sintered particle smaller than at least one second pore. The sintering process may be controlled to generate at least twenty to eighty percent of the first sintered particles having a size smaller than the plurality of second pores. The sintering pressure is in the range of 50 bars to 60 bars and the sintering temperature is in the range of 648.89 degrees Celsius to 815.56 degrees Celsius. The set of hollow sintering spacers 202 may be made of a material including nickel-cobalt ferrous alloy or ceramics such as aluminum nitrate, alumina, silicon carbide, and silicon nitride.

Further, the step 226 includes removing the set of hollow sintering spacers 202 and the sintering weight 212 from the first half casing portion 102 a.

The method 176 further includes a step 230 of filling a plurality of third particles 232 on the second sintered layer portion 128 a i.e. between the first set of 3-dimensional sintered projections 132. Further, at step 234 the plurality of third particles 232 are leveled using another squeegee device 236 having a uniform contact surface 238, so as to form a third layer portion 240 a having a uniform thickness “T₀₃”.

The method 176 further includes a step 242 of disposing another set of hollow sintering spacers 244 on the third layer portion 240 a and filling an additional amount of plurality of third particles 232 between the set of hollow sintering spacers 244.

The method 176 further includes a step 250 of sintering the third layer portion 240 a along with the additional amount of plurality of third particles 232. The sintering step 250 includes disposing the first half casing portion 102 a with the set of hollow sintering spacers 244 in the sintering device 224 to generate the third sintered layer portion 130 a as shown in step 254. Each hollow sintering spacer 244 has a uniform contact surface 252 to generate the third sintered layer portion 130 a having the uniform thickness “T₃”. The third sintered layer portion 130 a includes the plurality of third sintered particles 152 having the third porosity 164 and the plurality of third pores 162 (as shown in FIG. 3). The sintering process is performed in a controlled environment so as to generate the third porosity 164 smaller than the second porosity 160 and the third sintered particles 152 having a size less than or equal to the size of the second sintered particle 150.

Further, the step 254 includes removing the set of hollow sintering spacers 244 from the first half casing portion 102 a. A first wick portion 104 a is formed in the first half casing portion 102 a. The first wick portion 104 a includes the first sintered layer portion 126 a, the second sintered layer portion 128 a having the first set of 3-dimensional sintered projections 132, and the third sintered layer portion 130 a.

FIG. 6 a is a schematic flow diagram illustrating a plurality of steps involved in a method 258 of manufacturing the first sintered layer portion 126 b, the second sintered layer portion 128 b, and the third sintered layer portion 130 b within the second half casing portion 102 b in accordance with the embodiment of FIGS. 1 and 5.

The method 258 includes a step 260 of repeating the steps 178, 180, 186, and 192 in the second half casing portion 102 b to form the first layer portion 194 b and the second layer portion 196 b within the second half casing portion 102 b. The first layer portion 194 b is disposed on another coating portion 175 b. The coating portion 175 b may be applied to the inner surface 120 of the second half casing portion 102 b. The first layer portion 194 b has a uniform thickness “T₀₁” and the second layer portion 196 b has a uniform thickness “T₀₂”.

The method 258 further includes a step 262 of disposing a sintering weight 264 on the second sintered layer portion 196 b. The method further includes disposing the second half casing portion 102 b along with the sintering weight 264 in the sintering device 224 to sinter the first layer portion 194 b and the second layer portion 196 b so as to generate the first sintered layer portion 126 b and the second sintered layer portion 128 b as shown in step 266. The first sintered layer portion 126 b and the second sintered layer portion 128 b has a uniform thickness. The first sintered layer portion 126 b has the thickness “T₁” and the second sintered layer portion 128 b has the thickness “T₂”.

Further, the step 266 includes removing the sintering weight 264 from the second half casing portion 102 b. The step 266 further includes disposing another set of hollow sintering spacers 244 on the second sintered layer portion 128 b.

FIG. 6 b is a schematic flow diagram illustrating a plurality of steps involved in the method 258 of manufacturing the first sintered layer portion 126 b, the second sintered layer portion 128 b, and the third sintered layer portion 130 b within the second half casing portion 102 b in accordance with the embodiment of FIG. 6 a. The method 258 further includes a step 268 of filling the plurality of third particles 232 between the set of hollow sintering spacers 244 so as to form another third layer portion 248 b. The method 258 further includes a step 270 of sintering the other third layer portion 248 b. The sintering step 270 includes disposing the second half casing portion 102 b with the set of hollow sintering spacers 244 in the sintering device 224 to sinter the third layer portion 248 b so as to generate the third sintered layer portion 130 b as shown in step 272. The third sintered layer portion 130 b has a uniform thickness “T₃”. Further, the step 272 includes removing the set of hollow sintering spacers 244. A second wick portion 104 b is formed in the second half casing portion 102 b.

FIG. 7 is a schematic flow diagram illustrating a plurality of steps involved in a method 274 of coupling the first half casing portion 102 a to the second half casing portion 102 b to form the heat transfer device 100 in accordance with the embodiments of FIGS. 5 a, 5 b, 6 a, and 6 b.

The method 274 includes a step 276 of disposing the first half casing portion 102 a having the first wick portion 104 a. The method 274 further includes a step 278 of disposing the second half casing portion 102 b having the second wick portion 104 b. Further, the method 274 includes a step 280 of coupling the first half casing portion 102 a to the second half casing portion 102 b such that the first wick portion 104 a is coupled to the second wick portion 104 b to form the heat transfer device 100. A sealed chamber 106 is formed between the first half casing portion 102 a and the second half casing portion 102 b. The first set of 3-dimensional sintered projections 132 extends from one side 136 of the wick 104 towards other side 138 of the wick 104. The first half and second half casing portions 102 a, 102 b are coupled to each other by welding, brazing, soldering, or the like.

FIG. 8 a is a schematic flow diagram illustrating a method 300 of manufacturing a heat transfer device 399 in accordance with another exemplary embodiment.

The method 300 includes a step 302 of forming a first layer portion 304 a and a second layer portion 306 a within a first half casing portion 308 a. The first layer portion 304 a includes a plurality of first particles 310 and is disposed proximate to a coating portion 314 a of the first half casing portion 308 a. The second layer portion 306 a includes a plurality of second particles 312 and is disposed on the first layer portion 304 a. The method 300 further includes a step 316 of disposing a first set of hollow sintering spacers 318 and a second set of hollow sintering spacers 320 on the second layer portion 306 a. Each hollow sintering spacer 318 has a width “W₁” and each hollow sintering spacer 320 has a width “W₂” greater than width “W₁”. At step 324, an additional amount of the plurality of second particles 312 is filled between the first and second set of hollow sintering spacers 318, 320 to form a first set of 3-dimensional projections 326 and a second set of 3-dimensional projections 328. Further, a step 330 includes disposing a second set of hollow sintering spacers 332 on the first and second set of hollow sintering spacers 318, 320. Each hollow sintering spacer 332 has a width “W₃” equal or greater than the width “W₂” of each hollow sintering spacer 320.

FIG. 8 b is a schematic flow diagram illustrating the method 300 of manufacturing the heat transfer device 399 in accordance with the exemplary embodiment of FIG. 8 a. At step 334, an additional amount of the plurality of second particles 312 is filled between the second set of hollow sintering spacers 332 to form the second set 3-dimensional projections 336. The second set of 3-dimensional projections 328, 336 together form a second set of 3-dimensional projections 338.

The method 300 further includes a step 342 of sintering first layer portion 304 a, the second layer portion 306 a, and the first and second set of 3-dimensional projections 326, 338 in a sintering device 344 so as to generate the first sintered layer portion 346 a and the second sintered layer portion 348 a having a first set of 3-dimensional sintered projections 350 and second set of 3-dimensional sintered projections 352 as shown in step 354. The first set of 3-dimensional sintered projections 350 has a length “L₁” and the second set of 3-dimensional sintered projections 352 has a length “L₂”. The length “L₂” is greater than the length “L₁”. Further, the step 354 includes removing the first and second set of hollow sintering spacers 318, 320, 332 from the first half casing portion 308 a.

FIG. 8 c is a schematic flow diagram illustrating the method 300 of manufacturing the heat transfer device 399 in accordance with the exemplary embodiments of FIGS. 8 a and 8 b. The method 300 further includes a step 358 of filling a plurality of third particles 360 on the second sintered layer portion 348 a so as to form a portion of a third layer portion 362 i.e. between the first and second 3-dimensional sintered projections 350, 352. The method 300 further includes a step 364 of disposing another set of hollow sintering spacers 366 on the third layer portion 362 and the second set of 3-dimensional sintered projections 352 and then fill an additional amount of a plurality of third particles 360 between the set of hollow sintering spacers 366 so as to form a third layer portion 368. The layer portions 362, 368 together form a third layer portion 370 a. Each hollow sintering spacer 366 has a width “W₄”, which is greater than the width “W₂” or “W₃”.

The method 300 further includes a step 374 for sintering the third layer portion 370 a. The sintering step 374 includes disposing the first half casing portion 308 a with the set of hollow sintering spacers 366 in the sintering device 344 to sinter the third layer portion 370 a so as to generate a third sintered layer portion 376 a as shown in step 378. Further, the step 378 includes removing the set of hollow sintering spacers 366 from the first half casing portion 308 a. The first sintered layer portion 346 a, the second sintered layer portion 348 a having the first and second set of 3-dimensional sintered projections 350, 352, and the third sintered layer portion 376 a together form the first wick portion 380 a disposed within the first half casing portion 308 a.

FIG. 8 d is a schematic flow diagram illustrating the method 300 of manufacturing the heat transfer device 399 in accordance with the exemplary embodiments of FIGS. 8 a, 8 b, and 8 c. The method 300 further includes a step 382 of forming another first sintered layer portion 346 b and another second sintered layer portion 348 b within a second half casing portion 308 b. The method 300 further includes a step 384 of filling the plurality of third particles 360 on the second sintered layer portion 348 b so as to form another third layer portion 370 b. The method 300 further includes disposing a sintering weight 386 on the third layer portion 370 b and then sintering the third layer portion 370 b via the sintering device 344 so as to generate another third sintered layer portion 376 b as shown in step 388. The first sintered layer portion 346 b, the second sintered layer portion 348 b, and the third sintered layer portion 376 b together form a second wick portion 380 b disposed within the second half casing portion 308 b.

The method 300 further includes a step 390 of disposing the first half casing portion 308 a having the first wick portion 380 a. The method 300 further includes a step 392 of disposing the second half casing portion 308 b having the second wick portion 380 b. Further, the method 300 includes a step 394 for coupling the first half casing portion 308 a to the second half casing portion 308 b such that the first wick portion 380 a is coupled to the second wick portion 380 b to form the heat transfer device 399. The sealed chamber 375 is formed between the first half casing portion 308 a and the second half casing portion 308 b. The first wick portion 380 a and the second wick portion 380 b together form a wick 380. The first set of 3-dimensional sintered projections 350 extend from one side 396 towards another side 398 of the wick 380. The second set of 3-dimensional sintered projections 352 extend from one side 396 to the other side 398 of the wick 380. The first half and second half casing portions 308 a, 308 b are coupled to each other by welding, brazing, soldering, or the like.

FIG. 9 a is a schematic flow diagram illustrating a method 400 of manufacturing a heat transfer device 499 in accordance with yet another exemplary embodiment.

The method 400 includes a step 402 of forming a first layer portion 404 a and a second layer portion 406 a within a first half casing portion 408 a. The first layer portion 404 a includes a plurality of first particles 410 disposed proximate to a coating portion 414 a of the first half casing portion 408 a. The coating portion 414 a is disposed on the inner surface 407 of the first half casing portion 408 a. The second layer portion 406 a includes a plurality of second particles 412 disposed over the first layer portion 404 a. The step 402 further includes disposing a first set of hollow sintering spacers 418 on the second layer portion 406 a. The first set of hollow sintering spacers 418 has a width “W₁” and length “L₁”. The method further includes a step 416 of filling an additional amount of the plurality of second particles 412 between the first set of hollow sintering spacers 418 to form a first set of 3-dimensional projections 426. The step 416 further includes sintering the first layer portion 404 a, the second layer portion 406 a, and the first set of 3-dimensional projections 426 using a sintering device 444 so as to generate a first sintered layer portion 446 a, the second sintered layer portion 448 a having a first set of 3-dimensional sintered projections 450 as shown in step 454.

The step 454 further includes removing the first set of hollow sintering spacers 418 from the first half casing portion 408 a. At step 458 a plurality of third particles 460 are filled on the second sintered layer portion 448 a so as to form a third layer portion 462. The step 458 further includes disposing another first set of hollow sintering spacers 466 on the third layer portion 462. Further, the step 458 includes filling an additional amount of the plurality of third particles 460 between the first set of hollow sintering spacers 466 so as to form a third layer portion 468. The layer portions 462, 468 collectively form a third layer portion 470 a. The first set of hollow sintering spacers 466 has a width “W₂” and length “L₂”. The width “W₂” is greater than width “W₁” and length “L₁” is greater than length “L₂”.

The method 400 further includes a step 474 for sintering the third layer portion 470 a via the sintering device 444 so as to generate a third sintered layer portion 476 a as shown in step 478. Further, the step 478 includes removing the set of first hollow sintering spacers 466 from the first half casing portion 408 a. The first sintered layer portion 446 a, the second sintered layer portion 448 a having the first set of 3-dimensional sintered projections 450, and the third sintered layer portion 476 a together form a first wick portion 480 a within the first half casing portion 408 a.

FIG. 9 b is a schematic flow diagram illustrating the method 400 of manufacturing the heat transfer device 499 in accordance with the exemplary embodiment of FIG. 9 a. The method 400 further includes a step 482 of disposing a second set of hollow sintering spacers 420 on a second half casing portion 408 b having another second layer portion 406 b disposed on another first layer portion 404 b. The first layer portion 404 b is disposed proximate to another coating portion 414 b. The coating portion 414 b is disposed on the inner surface 407 of the second half casing portion 408 b. The second set of hollow sintering spacers 420 has a width “W₃” and length “L₃”. The width “W₃” is greater than the width “W₁” and length “L₃” is greater than length “L₁”. The method further includes a step 484 of filling an additional amount of the plurality of second particles 412 between the second set of hollow sintering spacers 420 to form a second set of 3-dimensional projections 438.

The step 484 further includes sintering the first layer portion 404 b, the second layer portion 406 b and the second set of 3-dimensional projections 438 via the sintering device 444 so as to generate another first sintered layer portion 446 b and another second sintered layer portion 448 b having a second set of 3-dimensional sintered projections 452 as shown in step 494. Further, the step 494 includes removing the second set of hollow sintering spacers 420 from the second half casing portion 408 b.

The method 400 further includes a step 496 of filling a plurality of third particles 460 on the second sintered layer portion 448 b so as to form a third layer portion 472 i.e. between the second set of 3-dimensional sintered projections 452. The step 496 further includes disposing another second set of hollow sintering spacers 422 on the third layer portion 472. Further, the step 496 includes filling an additional amount of the plurality of third particles 460 between the second set of hollow sintering spacers 422 so as to form a third layer portion 486. The layer portions 472, 486 together form a third layer portion 470 b. The second set of hollow sintering spacers 422 has a width “W₄” and length “L₄”. The width “W₄” is greater than the width “W₃” and length “L₃” is greater than length “L₄”.

The method 400 further includes a step 498 for sintering the third layer portion 470 b via the sintering device 444 so as to generate another third sintered layer portion 476 b as shown in step 500. Further, the step 500 includes removing the set of second hollow sintering spacers 422 from the second half casing portion 408 b. The first sintered layer portion 446 b, the second sintered layer portion 448 b having the second set of 3-dimensional sintered projections 452, and the third sintered layer portion 476 b together form a second wick portion 480 b within the second half casing portion 408 b.

FIG. 9 c is a schematic flow diagram illustrating the method 400 of manufacturing the heat transfer device 499 in accordance with the exemplary embodiments of FIGS. 9 a and 9 b. The method 400 further includes a step 502 of disposing the first half casing portion 408 a having the first wick portion 480 a. The method 400 further includes a step 504 of disposing the second half casing portion 408 b having the second wick portion 480 b.

Further, the method 400 includes a step 506 of coupling the first half casing portion 408 a to the second half casing portion 408 b such that the first wick portion 480 a is coupled to the second wick portion 480 b to form the heat transfer device 499. A sealed chamber 508 is formed between the first half casing portion 408 a and the second half casing portion 408 b. The first wick portion 480 a and the second wick portion 480 b together form a wick 480. The first set of 3-dimensional sintered projections 450 extend from one side 510 towards another side 512 of the wick 480. The second set of 3-dimensional sintered projections 452 extend from one side 510 to the other side 512 of the wick 480. The first half and second half casing portions 408 a, 408 b are coupled to each other by welding, brazing, soldering, or the like.

Embodiments of the present invention discussed herein facilitate easy and economic manufacturing of the heat transfer device. Further, the heat transfer device of the present invention provides lower thermal resistance, higher thermal conductivity, and higher heat transport capability. 

1. A heat transfer device comprising: a casing having an inner surface and an outer surface; and a wick disposed within the casing, wherein the wick comprises: a first sintered layer comprising a plurality of first sintered particles, having a first porosity and a plurality of first pores, disposed proximate to the inner surface of the casing; a second sintered layer comprising a plurality of second sintered particles, having a second porosity and a plurality of second pores, disposed on the first sintered layer, and at least one set of a first set of 3-dimensional sintered projections and a second set of 3-dimensional sintered projections disposed along a portion of the wick, wherein at least one first sintered particle is smaller than at least one second pore, the first porosity is smaller than the second porosity; and a third sintered layer including a plurality of third sintered particles, having a plurality of third pores and a third porosity smaller than the second porosity, disposed on at least a portion of the second sintered layer.
 2. The heat transfer device of claim 1, wherein a size of each third sintered particle is less than or equal to a size of each second sintered particle.
 3. The heat transfer device of claim 1, further comprising a coating disposed between the first sintered layer and the inner surface of the casing.
 4. The heat transfer device of claim 3, wherein the casing comprises a first material and the first sintered layer, the second sintered layer, the third sintered layer, and the coating comprises a second material different from the first material.
 5. The heat transfer device of claim 1, wherein the heat transfer device further comprises an evaporator section, a transport section, and a condenser section within the casing.
 6. The heat transfer device of claim 5, wherein the portion of the wick is disposed in at least one of the evaporator section and the condenser section.
 7. The heat transfer device of claim 1, wherein the first set of 3-dimensional sintered projections extends from a first side of the wick towards a second side of the wick.
 8. The heat transfer device of claim 7, wherein the first set of 3-dimensional sintered projections enhances a surface area of the wick and is configured to convert a working fluid from one phase to another phase.
 9. The heat transfer device of claim 1, wherein the second set of 3-dimensional sintered projections extends from a first side of the wick to a second side of the wick.
 10. The heat transfer device of claim 9, wherein the second set of 3-dimensional sintered projections provides structural support to the heat transfer device and is configured to transport a working fluid from the second side to the first side of the wick or vice versa.
 11. The heat transfer device of claim 1, wherein the first set of 3-dimensional sintered projections has a first width and the second set of 3-dimensional sintered projections has a second width greater than the first width.
 12. A method comprising: forming a first wick portion having a first sintered layer portion, a second sintered layer portion, and a third sintered layer portion, within a first half casing portion; forming a second wick portion having another first sintered layer portion, another second sintered layer portion, and another third sintered layer portion, within a second half casing portion; and coupling the first half casing portion to the second half casing portion such that the first wick portion is coupled to the second wick portion to form a heat transfer device; wherein each first sintered layer portion comprises a plurality of first sintered particles, having a first porosity and a plurality of first pores, each second sintered layer portion comprises a plurality of second sintered particles, having a plurality of second pores and a second porosity greater than the first porosity, at least one second sintered layer portion comprises a set of 3-dimensional sintered projections, and each third sintered layer portion comprises a plurality of third sintered particles, having a plurality of third pores and a third porosity, wherein at least one first sintered particle is smaller than at least one second pore.
 13. The method of claim 12, further comprising leveling a plurality of first particles and a plurality of second particles filled in both the first half casing portion and the second half casing portion.
 14. The method of claim 13, further comprising vibrating the first half casing portion to segregate the plurality of first particles from the plurality of second particles such that a first layer portion having the plurality of first particles is disposed proximate to an inner surface of the first half casing portion and a second layer portion having the plurality of second particles is disposed on the first layer portion.
 15. The method of claim 14, further comprising vibrating the second half casing portion to segregate the plurality of first particles from the plurality of second particles such that another first layer portion having the plurality of first particles is disposed proximate to another inner surface of the second half casing portion and another second layer portion having the plurality of second particles is disposed on the other first layer portion.
 16. The method of claim 15, further comprising providing a coating between the inner surface of each casing portion among the first and second half casing portion and each layer portion among the first layer portion and the other first layer portion; wherein each casing portion comprises a first material and each first layer portion, second layer portion and the coating comprises a second material different from the first material.
 17. The method of claim 15, further comprising disposing a set of hollow sintering spacers on a portion of at least one second layer portion and filling an additional amount of the plurality of second particles between the set of hollow sintering spacers to form a set of 3-dimensional projections on the portion of the at least one second layer portion.
 18. The method of claim 17, further comprising disposing the set of hollow sintering spacers on the portion of the corresponding second layer portion in one casing portion among the first and second half casing portions; wherein the set of hollow sintering spacers comprises a first set of hollow sintering spacers and a second set of hollow sintering spacers disposed on another second set of hollow sintering spacers, each first set of hollow sintering spacer has a first width, and each second set of hollow sintering spacer has a second width.
 19. The method of claim 18, further comprising filling an additional amount of the plurality of second particles between the first and second set of hollow sintering spacers to form a first set of 3-dimensional projections between the first set of hollow sintering spacers and a second set of 3-dimensional projections between the second set of hollow sintering spacers.
 20. The method of claim 19, further comprising sintering each first layer portion, each second layer portion, and the first and second set of 3-dimensional projections to generate the first sintered layer portion, the other first sintered layer portion, the second sintered layer portion, the other second sintered layer portion, the first set of 3-dimensional sintered projections, and the second set of 3-dimensional sintered projections.
 21. The method of claim 20, further comprising coupling the first half casing portion to the second half casing portion such that the second set of 3-dimensional projections in one half casing portion among the first and second half casing portion is coupled to the corresponding second layer portion of the other half casing portion among the first and second half casing portion.
 22. The method of claim 17, further comprising disposing a first set of hollow sintering spacers among the set of hollow sintering spacers, on the portion of the corresponding second layer portion in one casing portion among the first and second half casing portions and a second set of hollow sintering spacers among the set of hollow sintering spacers on the portion of the corresponding second layer portion in another casing portion among the first and second half casing portions; wherein each first set of hollow sintering spacer has a first width and a first height and each second set of hollow sintering spacer has a second width and a second height; wherein second width is greater than the first width and the second height is greater than the first height.
 23. The method of claim 22, further comprising filling an additional amount of the plurality of second particles between the first and second set of hollow sintering spacers to form a first set of 3-dimensional projections between the first set of hollow sintering spacers and a second set of 3-dimensional projections between the second set of hollow sintering spacers.
 24. The method of claim 23, further comprising sintering each first layer portion, each second layer portion, and the first and second set of 3-dimensional projections via a sintering device, to generate the first sintered layer portion, the other first sintered layer portion, the second sintered layer portion, the other second sintered layer portion, the first set of 3-dimensional sintered projections, and the second set of 3-dimensional sintered projections.
 25. The method of claim 24, further comprising coupling the first half casing portion to the second half casing portion such that the second set of 3-dimensional projections on the portion of the corresponding second layer portion in the other casing portion among the first and second half casing portions is coupled to the portion of corresponding second layer portion of the one half casing portion among the first and second half casing portions.
 26. The method of claim 17, further comprising disposing another set of hollow sintering spacers on at least a portion of the set of 3-dimensional sintered projections, filling a plurality of third particles on at least the portion of each second sintered layer portion and between the other set of hollow sintering spacers to form a third layer portion.
 27. The method of claim 26, further comprising sintering the third layer portion to generate the third sintered layer portion, wherein the third porosity is smaller than the second porosity. 